Sequoiadendron giganteum (giant sequoia; also known as giant redwood, Sierra redwood, Sierran redwood, Wellingtonia or simply big tree—a nickname also used by John Muir[2]) is the sole living species in the genus Sequoiadendron, and one of three species of coniferoustrees known as redwoods, classified in the family Cupressaceae in the subfamily Sequoioideae, together with Sequoia sempervirens (coast redwood) and Metasequoia glyptostroboides (dawn redwood). Giant sequoia specimens are the most massive trees on Earth.[3] The common use of the name sequoia usually refers to Sequoiadendron giganteum, which occurs naturally only in groves on the western slopes of the Sierra Nevada Mountains of California.

The etymology of the genus name has been presumed—initially in The Yosemite Book by Josiah Whitney in 1868[4]—to be in honor of Sequoyah (1767–1843), who was the inventor of the Cherokee syllabary.[5] An etymological study published in 2012, however, concluded that the name was more likely to have originated from the Latin sequi (meaning to follow) since the number of seeds per cone in the newly-classified genus fell in mathematical sequence with the other four genera in the suborder.[6]

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Giant sequoia specimens are the most massive individual trees in the world.[3] They grow to an average height of 50–85 m (164–279 ft) with trunk diameters ranging from 6–8 m (20–26 ft). Record trees have been measured at 94.8 m (311 ft) tall. Trunk diameters of 17 m (56 ft) have been claimed via research figures taken out of context.[7] The specimen known to have the greatest diameter at breast height is the General Grant tree at 8.8 m (28.9 ft).[8] Between 2014 and 2016, specimens of coast redwood were found to have greater trunk diameters than all known giant sequoias.[9] The trunks of coast redwoods taper at lower heights than those of giant sequoias which have more columnar trunks that maintain larger diameters to greater heights.

The oldest known giant sequoia is 3,500 years old based on dendrochronology. Giant sequoias are among the oldest living organisms on Earth. Giant sequoia bark is fibrous, furrowed, and may be 90 cm (3 ft) thick at the base of the columnar trunk. The bark provides significant protection from fire damage. The leaves are evergreen, awl-shaped, 3–6 mm (1⁄8–1⁄4 in) long, and arranged spirally on the shoots.

Giant sequoia cones and seed

The giant sequoia regenerates by seed. The seed cones are 4–7 cm (11⁄2–3 in) long and mature in 18–20 months, though they typically remain green and closed for as long as 20 years. Each cone has 30–50 spirally arranged scales, with several seeds on each scale, giving an average of 230 seeds per cone. Seeds are dark brown, 4–5 mm (0.16–0.20 in) long, and 1 mm (0.04 in) broad, with a 1-millimeter (0.04 in) wide, yellow-brown wing along each side. Some seeds shed when the cone scales shrink during hot weather in late summer, but most are liberated by insect damage or when the cone dries from the heat of fire. Young trees start to bear cones after 12 years.

Trees may produce sprouts from their stumps subsequent to injury, until about 20 years old; however, shoots do not form on the stumps of mature trees as they do on coast redwoods. Giant sequoias of all ages may sprout from their boles when branches are lost to fire or breakage.

A large tree may have as many as 11,000 cones. Cone production is greatest in the upper portion of the canopy. A mature giant sequoia disperses an estimated 300–400 thousand seeds annually. The winged seeds may fly as far as 180 m (590 ft) from the parent tree.

Lower branches die readily from being shaded, but trees younger than 100 years retain most of their dead branches. Trunks of mature trees in groves are generally free of branches to a height of 20–50 m (70–160 ft), but solitary trees retain lower branches.

Because of its size, the tree has been studied for its water pull. Water from the roots can be pushed up only a few meters by osmotic pressure but can reach extreme heights by using a system of branching capillarity (capillary action) in the tree's xylem (the water tubules) and sub-pressure from evaporating water at the leaves.[10] Sequoias supplement water from the soil with fog, taken up through air roots, at heights to where the root water cannot be pulled.[11]

The natural distribution of giant sequoias is restricted to a limited area of the western Sierra Nevada, California. They occur in scattered groves, with a total of 68 groves (see list of sequoia groves for a full inventory), comprising a total area of only 144.16 km2 (35,620 acres). Nowhere does it grow in pure stands, although in a few small areas, stands do approach a pure condition. The northern two-thirds of its range, from the American River in Placer County southward to the Kings River, has only eight disjunct groves. The remaining southern groves are concentrated between the Kings River and the Deer Creek Grove in southern Tulare County. Groves range in size from 12.4 km2 (3,100 acres) with 20,000 mature trees, to small groves with only six living trees. Many are protected in Sequoia and Kings Canyon National Parks and Giant Sequoia National Monument.

The giant sequoia is usually found in a humid climate characterized by dry summers and snowy winters. Most giant sequoia groves are on granitic-based residual and alluvial soils. The elevation of the giant sequoia groves generally ranges from 1,400–2,000 m (4,600–6,600 ft) in the north, to 1,700–2,150 metres (5,580–7,050 ft) to the south. Giant sequoias generally occur on the south-facing sides of northern mountains, and on the northern faces of more southerly slopes.

High levels of reproduction are not necessary to maintain the present population levels. Few groves, however, have sufficient young trees to maintain the present density of mature giant sequoias for the future. The majority of giant sequoias are currently undergoing a gradual decline in density since European settlement.

While the present day distribution of this species is limited to a small area of California, it was once much more widely distributed in prehistoric times, and was a reasonably common species in North American and Eurasian coniferous forests until its range was greatly reduced by the last ice age. Older fossil specimens reliably identified as giant sequoia have been found in Cretaceous era sediments from a number of sites in North America and Europe, and even as far afield as New Zealand[12] and Australia.[13]

Two giant sequoias, Sequoia National Park. The right-hand tree bears a large fire scar at its base; fires do not typically kill the trees but do remove competing thin-barked species, and aid giant sequoia regeneration.

Giant sequoias are in many ways adapted to forest fires. Their bark is unusually fire resistant, and their cones will normally open immediately after a fire.[15] The giant sequoias are having difficulty reproducing in their original habitat (and very rarely reproduce in cultivation) due to the seeds only being able to grow successfully in full sun and in mineral-rich soils, free from competing vegetation. Although the seeds can germinate in moist needle humus in the spring, these seedlings will die as the duff dries in the summer. They therefore require periodic wildfire to clear competing vegetation and soil humus before successful regeneration can occur. Without fire, shade-loving species will crowd out young sequoia seedlings, and sequoia seeds will not germinate. When fully grown, these trees typically require large amounts of water and are therefore often concentrated near streams.

Fires also bring hot air high into the canopy via convection, which in turn dries and opens the cones. The subsequent release of large quantities of seeds coincides with the optimal postfire seedbed conditions. Loose ground ash may also act as a cover to protect the fallen seeds from ultraviolet radiation damage.

Due to fire suppression efforts and livestock grazing during the early and mid 20th century, low-intensity fires no longer occurred naturally in many groves, and still do not occur in some groves today. The suppression of fires leads to ground fuel build-up and the dense growth of fire-sensitive white fir, which increases the risk of more intense fires that can use the firs as ladders to threaten mature giant sequoia crowns. Natural fires may also be important in keeping carpenter ants in check.[16]

In 1970, the National Park Service began controlled burns of its groves to correct these problems. Current policies also allow natural fires to burn. One of these untamed burns severely damaged the second-largest tree in the world, the Washington tree, in September 2003, 45 days after the fire started. This damage made it unable to withstand the snowstorm of January 2005, leading to the collapse of over half the trunk.

In addition to fire, two animal agents also assist giant sequoia seed release. The more significant of the two is a longhorn beetle (Phymatodes nitidus) that lays eggs on the cones, into which the larvae then bore holes. Reduction of the vascular water supply to the cone scales allows the cones to dry and open for the seeds to fall. Cones damaged by the beetles during the summer will slowly open over the next several months. Some research indicates many cones, particularly higher in the crowns, may need to be partially dried by beetle damage before fire can fully open them. The other agent is the Douglas squirrel (Tamiasciurus douglasi) that gnaws on the fleshy green scales of younger cones. The squirrels are active year round, and some seeds are dislodged and dropped as the cone is eaten.[17]

Shortly after their discovery by Europeans, giant sequoias were subject to much exhibition

The giant sequoia was well known to Native American tribes living in its area. Native American names for the species include wawona, toos-pung-ish and hea-mi-withic, the latter two in the language of the Tule River Tribe.

The first reference to the giant sequoia by Europeans is in 1833, in the diary of the explorer J. K. Leonard; the reference does not mention any locality, but his route would have taken him through the Calaveras Grove.[18] This discovery was not publicized. The next European to see the species was John M. Wooster, who carved his initials in the bark of the 'Hercules' tree in the Calaveras Grove in 1850; again, this received no publicity. Much more publicity was given to the "discovery" by Augustus T. Dowd of the Calaveras Grove in 1852, and this is commonly cited as the species' discovery.[18] The tree found by Dowd, christened the 'Discovery Tree', was felled in 1853.

The first scientific naming of the species was by John Lindley in December 1853, who named it Wellingtonia gigantea, without realizing this was an invalid name under the botanical code as the name Wellingtonia had already been used earlier for another unrelated plant (Wellingtonia arnottiana in the family Sabiaceae). The name "Wellingtonia" has persisted in England as a common name.[19] The following year, Joseph Decaisne transferred it to the same genus as the coast redwood, naming it Sequoia gigantea, but again this name was invalid, having been applied earlier (in 1847, by Endlicher) to the coast redwood. The name Washingtonia californica was also applied to it by Winslow in 1854, though this too is invalid, belonging to the palm genus Washingtonia.

In 1907, it was placed by Carl Ernst Otto Kuntze in the otherwise fossil genus Steinhauera, but doubt as to whether the giant sequoia is related to the fossil originally so named makes this name invalid.

The nomenclatural oversights were finally corrected in 1939 by J. Buchholz, who also pointed out the giant sequoia is distinct from the coast redwood at the genus level and coined the name Sequoiadendron giganteum for it.

The etymology of the genus name has been presumed—initially in The Yosemite Book by Josiah Whitney in 1868[4]—to be in honor of Sequoyah (1767–1843), who was the inventor of the Cherokee syllabary.[5] An etymological study published in 2012, however, concluded that the name was more likely to have originated from the Latin sequi (meaning to follow) since the number of seeds per cone in the newly-classified genus fell in mathematical sequence with the other four genera in the suborder.[6]

"Do behold the King in his glory, King Sequoia! Behold! Behold! seems all I can say. Some time ago I left all for Sequoia and have been and am at his feet, fasting and praying for light, for is he not the greatest light in the woods, in the world? Where are such columns of sunshine, tangible, accessible, terrestrialized?' [20]

Wood from mature giant sequoias is highly resistant to decay, but due to being fibrous and brittle, it is generally unsuitable for construction. From the 1880s through the 1920s, logging took place in many groves in spite of marginal commercial returns. The Hume-Bennett Lumber Company was the last to harvest giant sequoia, going out of business in 1924.[21] Due to their weight and brittleness, trees would often shatter when they hit the ground, wasting much of the wood. Loggers attempted to cushion the impact by digging trenches and filling them with branches. Still, as little as 50% of the timber is estimated to have made it from groves to the mill. The wood was used mainly for shingles and fence posts, or even for matchsticks.

The wood from immature trees is less brittle, with recent tests on young plantation-grown trees showing it similar to coast redwood wood in quality. This is resulting in some interest in cultivating giant sequoia as a very high-yielding timber crop tree, both in California and also in parts of western Europe, where it may grow more efficiently than coast redwoods. In the northwest United States, some entrepreneurs have also begun growing giant sequoias for Christmas trees. Besides these attempts at tree farming, the principal economic uses for giant sequoia today are tourism and horticulture.

Giant sequoia is a very popular ornamental tree in many areas. It is successfully grown in most of western and southern Europe, the Pacific Northwest of North America north to southwest British Columbia, the southern United States, southeast Australia, New Zealand and central-southern Chile. It is also grown, though less successfully, in parts of eastern North America.

Trees can withstand temperatures of −31 °C (−25 °F) or colder for short periods of time, provided the ground around the roots is insulated with either heavy snow or mulch. Outside its natural range, the foliage can suffer from damaging windburn.

The tallest giant sequoia ever measured outside of the United States[23] is a specimen planted near Ribeauvillé in France in 1856 and measured in 2014 at a height between 57.7 m (189 ft)[24] and 58.1 m (191 ft)[25] at age 158 years.

The giant sequoia was first brought into cultivation in Britain in 1853 by the horticulturist Patrick Matthew of Perthshire from seeds sent by his botanist son John in California.[26] A much larger shipment of seed collected from the Calaveras Grove by William Lobb, acting for the Veitch Nursery near Exeter, arrived in England in December 1853;[27] seed from this batch was widely distributed throughout Europe.

Growth in Britain is very fast, with the tallest tree, at Benmore in southwest Scotland, reaching 56.4 m (185 ft) in 2014 at age 150 years,[28] and several others from 50–53 m (164–174 ft) tall; the stoutest is around 12 m (39 ft) in girth and 4 m (13 ft) in diameter, in Perthshire. The Royal Botanic Gardens at Kew in London also contains a large specimen. Biddulph Grange Garden in Staffordshire holds a fine collection of both Sequoiadendron giganteum and Sequoia sempervirens (coast redwood). The General Sherman of California has a volume of 1,489 m3 (52,600 cu ft); by way of comparison, the largest giant sequoias in Great Britain have volumes no greater than 90–100 m3 (3,200–3,500 cu ft), one example being the 90 m3 (3,200 cu ft) specimen in the New Forest.

Sequoiadendron giganteum at New Forest, Hampshire, England, one of the tallest in the UK at 52.73 m (173.0 ft).[29]

Numerous giant sequoia were planted in Italy from 1860 through 1905. Several regions contain specimens that range from 40 to 48 metres (131 to 157 ft) in height. The largest tree is in Roccavione, in the Piedmont, with a basal circumference of 16 metres (52 ft). One notable tree survived a 200-metre (660 ft) tall flood wave in 1963 that was caused by a landslide at Vajont Dam. There are numerous giant sequoia in parks and reserves.[33]

Growth rates in some areas of Europe are remarkable. One young tree in Italy reached 22 m (72 ft) tall and 88 cm (2.89 ft) trunk diameter in 17 years (Mitchell, 1972).

Growth further northeast in Europe is limited by winter cold. In Denmark, where extreme winters can reach −32 °C (−26 °F), the largest tree was 35 m (115 ft) tall and 1.7 m (5.6 ft) diameter in 1976 and is bigger today. One in Poland has purportedly survived temperatures down to −37 °C (−35 °F) with heavy snow cover.

Two members of the German Dendrology Society, E. J. Martin and Illa Martin, introduced the giant sequoia into German forestry at the Sequoiafarm Kaldenkirchen in 1952.[34]

Giant sequoias are grown successfully in the Pacific Northwest and southern US, and less successfully in eastern North America. Giant sequoia cultivation is very successful in the Pacific Northwest from western Oregon north to southwest British Columbia, with fast growth rates. In Washington and Oregon, it is common to find giant sequoias that have been successfully planted in both urban and rural areas. In the Seattle area, large specimens exceeding 90 ft (27 m) are fairly common and exist in several city parks and many private yards (especially east Seattle including Capitol Hill, Washington Park, & Leschi/Madrona, as well as Tacoma's Jefferson Park).

Sequoiadendron giganteum "Hazel Smith", photographed at the U.S. National Arboretum in September, 2014.

A cold-tolerant cultivar 'Hazel Smith' selected in about 1960 is proving more successful in the northeastern US. This clone was the sole survivor of several hundred seedlings grown at a nursery in New Jersey. The U.S. National Arboretum has a specimen grown from a cutting in 1970 that can be seen in the Gotelli Conifer Collection.

The Ballarat Botanical Gardens contain a significant collection, many of them about 150 years old. Jubilee Park and the Hepburn Mineral Springs Reserve in Daylesford, Cook Park in Orange, New South Wales and Carisbrook's Deep Creek park in Victoria both have specimens. Jamieson Township in the Victorian high country has 2 specimens which were planted in the early 1860s.[41] In Tasmania specimens are to be seen in private and public gardens, as they were popular in the mid Victorian era. The Westbury Village Green has mature specimens with more in Deloraine. The Tasmanian Arboretum contains young wild collected material. The National Arboretum Canberra has begun a grove. They also grow in the abandoned arboretum at Mount Banda Banda in New South Wales.

The Washington Tree was previously arguably the second largest tree with a volume of 47,850 cubic feet (1,355 m3) (although the upper half of its trunk was hollow, making the calculated volume debatable), but after losing the hollow upper half of its trunk in January 2005 following a fire, it is no longer of great size.

^The volume figures have a low degree of accuracy (at best about ±14 cubic metres or 490 cubic feet), due to difficulties in measurement; stem diameter measurements are taken at a few set heights up the trunk, and assume that the trunk is circular in cross-section, and that taper between measurement points is even. The volume measurements also do not take cavities into account. The measurements are trunk-only, and do not include the volume of wood in the branches or roots.

^ abcd
This table presents giant sequoias sorted by the volume of their trunks. In December 2012, Stephen Sillett announced a measurement of the President tree with a total of 54,000 cubic feet (1,500 m3) of wood and 9,000 cubic feet (250 m3) of wood in the branches.[43][44] Ranked according to the total amount of wood in the tree, the General Sherman tree is first, the President tree is second, and the General Grant tree is third.[43][44] General Sherman has 2,000 cubic feet (57 m3) more wood than the President tree.[43]

^ abLowe, Gary D. (2012). "Endlicher's Sequence: The Naming of the Genus Sequoia"(PDF). cnps.org. California Native Plant Society. p. 33. Retrieved January 15, 2017. ...the foregoing has shown that the name of the genus Sequoia as a tribute to the Cherokee linguist Sequoyah is an unsubstantiated opinion...Endlicher named the genus for the operation that he had conducted. The new genus fell in sequence with the other four genera in his suborder.